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NETHERLANDS - New research is now taking place into the plant-fed blackworm as an alternative feed for farmed fish.

Wild fish are becoming increasingly scarce, so there is more and more demand for farmed fish. However, the problem is that the feed for farmed fish consists of fish meal made from fish.

For almost three years, Marine biologist Bob Laarhoven, who works at the Agrotechnology and Food Sciences Group of Wageningen University, has been doing his PhD research into a cultured worm that feeds on plant material. The aim of this research is to discover the best conditions for producing large quantities of these worms.

Plant material

The worms that figure in this research are generally known as blackworms. These worms convert low-grade materials into high-grade food substances such as proteins, sugars and fats. Their food source consists of plant waste. On average they grow to 6 cm long and weigh between 6 and 10 mg. They reproduce by constantly splitting in two. As all worms consist of an old and a new part, it is not possible to determine how old they are.

This research, unlike previous studies on worms, focuses on the valorisation of clean waste streams from the food industry. Many waste streams are full of food and thus suitable for this worm. For example, apple peel and cores from apple sauce factories, or the material that remains after distilling alcohol from wheat grains.

Worm reactor

For this research, Mr Laarhoven has developed a reactor containing a straining cloth in the form of a cylinder. The worms stick their heads inside and enjoy a constant stream of food. Mr Laarhoven hopes this will enable him to determine the best conditions for breeding these worms in mass production. It is also important to look at how much money would be saved by deploying worms in processing waste streams, as they process huge quantities of waste while only eating what they need.

Within a year a larger worm reactor will be built and used for carrying out a large-scale test. Mr Laarhoven is performing this research in collaboration with Wetsus Centre of Excellence for Sustainable Water Technology in Leeuwarden.